DNA Structure

DNA Structure DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix. A molecule of DNA is made up of millions of tiny subunits called Nucleotides. Each nucleotide consists of: A Phosphate group A sugar A Nitrogenous base

The Structure of A Nucleotide Phosphate Nitrogenous Base Pentose Sugar

DNA is Structured like a Ladder The phosphate and sugar molecules form the backbone of the DNA molecule the bases form the “rungs”. The “rungs” are made from Nitrogen Bases

The Four Types of Nucleotides A Adenine T Thymine C Cytosine G Guanine

The Nitrogen Bases Form a base pair. Form a base pair. Each base will only bond with one other specific base. Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Form a base pair. Form a base pair.

DNA Structure Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand. If you have a strand that is ATGC, the complementary strand will be ? Answer: TACG

A C T G G A T C

A Look At The DNA Code To crack the genetic code found in DNA we need to look at the sequence of bases. The bases are arranged in triplets called codons. A G G - C T C - A A G - T C C - T A G T C C - G A G - T T C - A G G - A T C

Deciphering The Genetic Code

Going from DNA to Proteins A gene is a section of DNA that codes for a protein. Each unique gene has a unique sequence of bases. This unique sequence of bases will code for the production of a unique protein. It is these proteins and combination of proteins that give us a unique phenotype.

What are Chromosomes? Chromosomes are condensed bundles of DNA. Long thin stands of DNA (chromatin) are wrapped around protein molecules (histones) to form organized bodies of DNA = Chromosomes

DNA Gene Protein Trait

The Central Dogma of Biology

DNA Replication During DNA Replication, DNA copies each strand of the DNA molecule. Each stand is copied which results in two identical copies

What Is RNA? RNA is also a Nucleic Acid There are three types of RNAs It is a single stranded molecule Uracil replaces thymine The Sugar is Ribose In DNA, sugar is Deoxyribose There are three types of RNAs mRNA tRNA rRNA RNA Stands for RiboseNucleic Acid

The Structure of RNA?

The Different Forms of RNA Each form of RNA has a very specific and different Job

Why Do We Need RNA? The genetic Code from DNA is transcribed into the RNA Code RNA carries the genetic information from the nucleus out into the cytoplasm Messenger RNA (mRNA) brings the genetic code to the Ribosomes, where the protein will be made

The Central Dogma of Biology

The Process of Transcription

Transcription: From DNA to RNA If the nitrogen bases on the DNA molecule are: A T G C Then the RNA Stand would be U A C G

The Process of Transcription mRNA is made and leaves the Nucleus

The Process of Translation mRNA attaches to a ribosome Translation begins at the AUG, start codon. The anticodon of the tRNA binds to the complimentary codon on the mRNA The corresponding amino acid is attached to the tRNA molecule

The Process of Protein Synthesis The ribosomes join the two amino acids together forming a peptide bond. The tRNA floats away from the ribosome and binds to its specific amino acid The ribosome advances along the mRNA strand binding new amino acids together

Translation: The Final Product The process continues until the ribosome reaches one of the three stop codons. The result is a complete polypeptide = protein

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